Heather and me, by Sir Paul

Sir Paul McCartney has admitted that his relationship with his girlfriend Heather Mills is 'very hard' for his family.

The former Beatle, who lost his wife Linda to breast cancer in 1998, told how his children did not at first accept him going out with the blonde former model.

'Well, it is very hard, not was,' he added. 'It's very difficult for anyone to step into that position.

'Linda and I had such a beautiful relationship for so many years that there's no question of replacing her, but even having said that, it's still difficult.

'The fact is that life goes on and I fancy Heather and the kids appreciate that. It was awkward, yeah, but it's getting better by the minute.'

Sir Paul and Linda had three children - Mary, Stella and the youngest, James, who still lives at home. He adopted Heather, Linda's daughter by a previous marriage.

Linda died at 56 after a two and a half year struggle against breast cancer.

Interviewed in this month's issue of Arena magazine, Sir Paul says being in a relationship with charity worker Miss Mills - who lost a leg after being hit by a motorcycle - is fulfilling and surprising.

They started dating in March last year, after meeting at an awards function the previous April.

The 58-year-old pop legend describes being with her as 'very nice, lovely, very surprising'.

He adds: 'Linda and I were very lucky. We were totally faithful to each other for 30 years 'cos there didn't seem any reason not to be and that, in most people's books, is amazingly lucky.

'After she died, I remember Ralph Lauren telling me "I couldn't go through all that again", and I know what he meant, but you don't know what's just around the corner.'

Sir Paul publicly declared his love for Heather on a television show in October last year. He said he fancied her as soon as they met.

'Obviously I'd been going through a hard time,' he said. 'Now I've got romance back into my life. I love her and I get a lot of pleasure from that.'

Reports that Heather, who campaigns for victims of landmines, does not get on with his children have always been strenuously denied.

The rumours have centred in particular on Miss Mills's relationship with fashion designer Stella. The two appeared pointedly to ignore each other at a fashion party last year.

At the time, a source close to Sir Paul said they did not greet each other simply because they did not want to be pictured together by a photographer whom they disliked. Sir Paul also tells Arena that Stella, who is quitting the Chloe label for Gucci, does not put him under pressure to look cool.

'She doesn't mind what I wear,' he says. 'I've got a real clapped out old comfortable glove of a farm jacket and she actually nicks it to wear.

'She's a really talented designer. She could take the easy route and use fur, but she's too ballsy and too sensible and way too cool to do that. She's ballsy enough to tell Madonna off for wearing fur in public and in private.